[ntp:questions] Ginormous offset and slow convergance

unruh unruh at invalid.ca
Wed Nov 30 17:03:41 UTC 2011

On 2011-11-30, Pete Ashdown <pashdown at xmission.com> wrote:
> David Woolley <david at ex.djwhome.demon.invalid> writes:
>>Richard B. Gilbert wrote:
>>> On 11/29/2011 1:42 PM, Pete Ashdown wrote:
>>>> +time-C.timefreq .ACTS.           1 u   19   64  377   37.887  
>>>> -16011.   0.122
>>>> Is there anything I can do to decrease the convergence time?
>>> Little or nothing!  NTPD can, and sometimes does, take ten hours to 
>>> reach "steady state".  It needs about thirty minutes to find a 
>>16 second excursions are not the result of ntpd convergence delays. 
>>They indicate something seriously broken.  Possibly something else is 
>>trying to set the time.
> Thanks for the pointer David.  I added the local hardware clock (
> to the ntp.conf and that nailed it down.  Now my convergence is under a
> minute!

Uh, that is NOT the local hardware clock. That is local system clock.
Ie, the clock you are trying to discipline with ntpd. 
Ie, you are setting the clock with itself, and so it will always have
zero offset-- super convergence, but unfortunately not to anything even
approximating the real time. 
In fact ntpd cannot have 16 sec excursions. If the offset to what ntpd
thinks is a valid time are greater than 128ms (.128 s) it will step the

What operating system are you using? What version of ntpd?

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